Display device

ABSTRACT

A display panel according to the present invention includes a display panel and a cover member disposed on the display panel. The cover member includes a glass plate that is chemically strengthened and has a first surface and a second surface in which the depth of the compressive stress layer (dol) is larger than that in the first surface, and an optical layer that is layered on the second surface and faces the outside.

TECHNICAL FIELD

The present invention relates to a display device, and a cover memberincluded in the display device.

BACKGROUND ART

Patent Literature 1 discloses a vehicle-mounted display device. In thisdisplay device, a cover member is fixed to the surface of a displaypanel, thereby protecting the display panel.

CITATION LIST Patent Literature

Patent Literature 1: WO 2017/208995

SUMMARY OF INVENTION Technical Problem

Since the cover member is provided for the purpose of protecting thedisplay panel, it is necessary to increase the strength of the covermember. If an accident occurs, for example, a driver or a person sittingon the passenger seat may collide against the cover member, andtherefore, it is necessary to protect the driver or the like at thistime. The present invention was made in order to solve theaforementioned problem, and it is an object thereof to provide a displaydevice capable of protecting a driver who collides against the displaydevice from impact with the display device, a cover member included inthe display device, and a method for manufacturing a cover member.

Solution to Problem

Item 1. A display device including:

a display panel; and

a cover member disposed on the display panel,

wherein the cover member includes:

-   -   a glass plate that is chemically strengthened and has a first        surface and a second surface in which a depth of a compressive        stress layer (dol) is larger than that in the first surface; and    -   an optical layer that is layered on the second surface of the        glass plate and faces the outside.

Item 2. The display device according to item 1, wherein the glass plateis manufactured using a float process, and a concentration of tin oxidein the first surface is larger than that in the second surface.

Item 3. The display device according to item 1 or 2, wherein the opticallayer is an organic-inorganic composite film.

Item 4. The display device according to any one of items 1 to 3,

wherein the optical layer contains at least a matrix and particles, and

the particles form protrusions and depressions on a surface of theoptical layer on a side opposite to the second surface.

Item 5. The display device according to claim 4, wherein the opticallayer includes a first region in which the particles are piled up in athickness direction of the film, and a valley-shaped second region thatsurrounds the first region or is surrounded by the first region.

Item 6. The display device according to claim 5, wherein the firstregion is a plateau-shaped region.

Item 7. The display device according to claim 5 or 6, wherein the secondregion includes a portion in which the particles are not piled up or theparticles are not present.

Item 8. The display device according to any one of claims 5 to 7,wherein the first region has a width of 7.7 μm or more, and the secondregion has a width of 7 μm or more.

Item 9. The display device according to any one of claims 5 to 7,wherein the first region has a width of 10 μm or more, and the secondregion has a width of 10 μm or more.

Item 10. The display device according to item 4,

wherein the particles are substantially composed of plate-shapedparticles,

each of the plate-shaped particles has a thickness within a range of 0.3nm to 3 nm and a main surface average diameter within a range of 10 nmto 1,000 nm, and

the main surfaces of the plate-shaped particles are orientedsubstantially in parallel with the second surface of the glass plate.

Item 11. The display device according to item 4, wherein the opticallayer includes a region in which the particles are piled up in athickness direction of the optical layer, and a region in which theparticles are not piled up or the particles are not present.

Item 12. The display device according to item 11, wherein a differencein height measured from the second surface of the glass plate betweenthe highest portion and the lowest portion of the optical layer is threetimes or more as large as the average particle diameter of theparticles.

Item 13. The display device according to item 11 or 12, wherein Smr1defined in ISO25178 is 10 to 30%.

Item 14. The display device according to any one of items 11 to 13,wherein a surface height BH20 at a load area ratio of 20% defined inISO25178 is within a range of 0.04 μm to 0.5 μm.

Item 15. The display device according to any one of claims 11 to 14,wherein a surface height BH80 at a load area ratio of 80% defined inISO25178 is within a range of −0.3 μm to 0 μm.

Item 16. The display device according to any one of items 1 to 15,

wherein the surface of the optical layer has an Rsm of more than 0 μmand 35 μm or less,

the Rsm being an average length of roughness curve elements determinedin accordance with JIS B0601: 2001.

Item 17. The display device according to any one of items 1 to 16,

wherein the surface of the optical layer has an Ra within a range of 20nm to 120 nm,

the Ra being an arithmetic average roughness of a roughness curvedetermined in accordance with JIS B0601: 2001.

Item 18. The display device according to any one of items 1 to 17,

wherein the second surface of the glass plate has an Ra of 10 nm orless,

the Ra being an arithmetic average roughness of a roughness curvedetermined in accordance with JIS B0601: 2001.

Item 19. The display device according to any one of items 1 to 18,wherein the matrix contains silicon oxide as a main component.

Item 20. The display device according to any one of items 1 to 19,wherein the glass plate has a thickness of 0.5 to 3 mm.

Item 21. A cover member to be included in a display device having adisplay panel, including:

a glass plate that is manufactured using a float process, and has afirst surface and a second surface in which a concentration of tin oxideis larger than that in the first surface; and

an optical layer that is layered on the second surface of the glassplate and faces the outside.

Advantageous Effects of the Invention

With the present invention, when a driver or the like collides against adisplay device, it is possible to protect the driver or the like fromimpact with the display device.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a plan view showing an embodiment of a display deviceaccording to the present invention.

FIG. 2 is a partial cross-sectional view of a cover member included inthe display device shown in FIG. 1 .

FIG. 3 is a perspective view showing an example of a particle containedin a first anti-glare film.

FIG. 4 is a cross-sectional view of a cover member in which a secondanti-glare film is layered.

FIG. 5 is a cross-sectional view of a cover member in which a secondanti-glare film is layered.

FIG. 6 is a cross-sectional view of a cover member in which a thirdanti-glare film is layered.

FIG. 7 is a cross-sectional view of a cover member in which a thirdanti-glare film is layered.

FIG. 8 is a schematic cross-sectional view showing a cross section of aprotrusion in a film of the cover member in which a third anti-glarefilm is layered.

FIG. 9 is a plan view showing an example of a shield layer.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment in which a display device according to thepresent invention is applied to a vehicle-mounted display device will bedescribed with reference to the drawings. FIG. 1 is a cross-sectionalview of a display device. Examples of the vehicle-mounted display deviceinclude a car navigation system, and a display device for displayingvarious meters and an operation panel.

1. Overview of Display Device

As shown in FIG. 1 , the display device according to this embodimentincludes a housing 4 provided with an opening, a display panel 500 and abacklight unit 6 that are housed in the housing 4, and a cover member100 that covers the opening of the housing 4. Hereinafter, the memberswill be described in detail.

2. Housing

The housing 4 includes a rectangular bottom wall portion 41, and a sidewall portion 42 that rises from the peripheral edge of the side wallportion 41, and the above-described display panel 500 and backlight unit6 are housed in the internal space surrounded by the bottom wall portion41 and the side wall portion 42. The above-described cover member 100 isattached so as to cover the opening formed by the upper end portion ofthe side wall portion 42. Although the material of the housing 4 is notparticularly limited, the housing 4 can be formed using, for example, aresin material, metal, or the like.

3. Display Panel and Backlight Unit

A known liquid crystal panel can be used as the display panel 500. Thebacklight unit 6 is configured to emit light toward the liquid crystalpanel, and some backlight units formed by layering a diffusion sheet, alight-guiding plate, a light source such as an LED, a reflection sheet,and the like are known. Note that an organic EL panel, a plasma displaypanel, an electronic ink-type panel, and the like can be employed as thedisplay panel 500 instead of a liquid crystal panel, for example. If thedisplay panel 500 is constituted by a display panel other than a liquidcrystal panel, there is no need to provide the backlight unit.

4. Cover Member

The cover member 100 includes a glass plate 10 having a first surfaceand a second surface, an adhesive layer 3 layered on the first surfaceof the glass plate 10, and an optical layer 20 layered on the secondsurface. The cover member 100 is configured such that the first surfaceof the glass plate 10 faces the display panel 500 and the second surfacethereof faces the outside of the display device, that is, a driver inthis embodiment. A more detailed description will be given below.

4-1. Glass Plate

The glass plate 10 can be made of, for example, general-purposesoda-lime glass, borosilicate glass, aluminosilicate glass, alkali-freeglass, or other types of glass. Moreover, the glass plate 10 can beformed using a float process. This production process makes it possibleto obtain a glass plate 10 having a flat and smooth surface. However,the glass plate 10 may have protrusions and depressions on a mainsurface thereof, and may be made of, for example, figured glass. Figuredglass can be formed using a production process known as a roll-outprocess. Figured glass that is formed using this production processusually has periodic protrusions and depressions in one direction alongthe main surface of the glass plate.

In the float process, molten glass is continuously supplied onto amolten metal such as molten tin, and the supplied molten glass is madeto flow over the molten metal and thereby formed into a strip-likeshape. The thus formed glass is called a “glass ribbon”.

The glass ribbon is cooled as it moves downstream, and the cooled andsolidified glass ribbon is raised from the molten metal by rollers.Then, the glass ribbon is transported to an annealing lehr by rollers,annealed, and then cut. In this manner, a float glass plate can beobtained. Here, in float glass plate, a surface that has been in contactwith the molten metal is referred to as a “bottom surface”, and asurface opposite to the bottom surface is referred to as a “topsurface”. The bottom surface and the top surface may be unpolishedsurfaces. Note that, since the bottom surface has been in contact withthe molten metal, the concentration of tin oxide contained in the bottomsurface is larger than the concentration of tin oxide contained in thetop surface in the case where the molten metal is molten tin. In thisembodiment, the first surface of the glass plate 10 corresponds to thebottom surface, and the second surface corresponds to the top surface.

Although the thickness of the glass plate 10 formed as mentioned aboveis not particularly limited, a thin glass plate is better for weightreduction. For example, the thickness thereof is preferably 0.5 to 3 mm,and more preferably 0.6 to 2.5 mm. The reason for this is that, if theglass plate 10 is excessively thin, the strength is reduced, whereas, ifthe glass plate 10 is excessively thick, an image on the display panel500 may be distorted when seen through the cover member 100. The surfaceroughness Ra of the second surface of the glass plate 10 is preferably10 nm or less, more preferably 5 nm or less, even more preferably 2 nmor less, and particularly preferably 1 nm or less. With thisconfiguration, in a case where an anti-glare film is used as the opticallayer as described later, anti-glare properties become prominent.

Typically, the glass plate 10 is preferably a flat plate, but may alsobe a curved plate. In particular, in the case where the image displaysurface of the display panel 500 to be combined with the glass plate 10has a non-flat surface shape such as a curved surface, it is preferablethat the glass plate 10 has a main surface with a non-flat surface shapethat fits the non-flat surface shape of the image display surface. Inthis case, the entire glass plate 10 may be curved so as to have acertain curvature, or the glass plate 10 may be locally curved.

Each of the main surfaces (the first surface and the second surface) ofthe glass plate 10 may be constituted by, for example, a plurality offlat surfaces being connected via curved surfaces. The radius ofcurvature of the glass plate 10 is, for example, 5,000 mm or less. Thisradius of curvature is, for example, 10 mm or more, but in particular, alocally curved portion may have an even smaller radius of curvature(e.g., 1 mm or more). The wording “main surfaces” as used herein refersto surfaces on the front and back sides other than side surfaces.

The optical layer 20 may be configured to cover the second surface ofthe glass plate 10 entirely or partially. In the latter case, it issufficient that the optical layer is formed on at least a portion of thesecond surface that covers the image display surface of the displaypanel 500.

The glass plate 10 is chemically strengthened. This will be described indetail. There is no particular limitation on a chemical strengtheningprocess. For example, a glass plate 1 can be chemically strengthened byperforming an ion exchange treatment in which a glass plate thatcontains sodium is brought into contact with a molten salt that containsmonovalent cations, preferably potassium ions, that have a larger ionicradius than sodium ions, and sodium ions in the glass plate 1 arereplaced with the above-mentioned monovalent cations. A compressivestress layer in which compressive stress is applied is thus formed inthe surface of the glass plate 10.

A typical example of the molten salt is that of potassium nitrate.Although a mixed molten salt of potassium nitrate and sodium nitrate maybe used, a molten salt of potassium nitrate alone is preferable becauseit is difficult to control the concentration of the mixed molten salt.

The surface compressive stress and the depth of the compressive stresslayer of the glass plate 10 can be controlled by adjusting not only theglass composition but also the temperature of the molten salt during theion exchange treatment and the treatment time. The treatment temperaturein the ion exchange treatment can be set to, for example, 360 to 460° C.Note that the treatment temperature for the glass plate 10 having acomposition for the above-described chemical strengthening is preferablyhigher, and can be set to, for example, 400 to 460° C.

Incidentally, since the glass plate 10 of this embodiment ismanufactured using the float process as described above, theconcentration of tin oxide in the top surface is smaller than that inthe bottom surface. Accordingly, when the above-described chemicalstrengthening is performed, the depth of the compressive stress layer(dol) in the top surface is larger than the depth of the compressivestress layer in the bottom surface. Depending on the conditions such asthe composition of the glass plate and the temperature, the larger thedepth of the compressive stress layer is, the smaller the compressivestress tends to be. Accordingly, the surface compressive stress of thetop surface, that is, the second surface of the glass plate 10, issmaller than that of the first surface. Specifically, when chemicalstrengthening is performed on the top surface and bottom surface of theglass plate 10 under the same conditions, the depth of the compressivestress layer in the second surface is larger by about 1 to 10 μm thanthat in the first surface, and thus the surface compressive stress ofthe second surface is smaller by about 30 to 180 MPa than the surfacecompressive stress of the first surface. The depth of the compressivestress layer can be measured using, for example, a surface stress meter.

For example, the inventor of the present invention obtained thefollowing test results from chemical strengthening performed on the topsurface and bottom surface of the glass plate 10 under the sameconditions. That is, the depth of the compressive stress layer in thetop surface was 10 to 20 μm, and the surface compressive stress was 650to 800 MPa at this time. On the other hand, the depth of the compressivestress layer in the bottom surface was 9 to 19 μm, and the surfacecompressive stress was 680 to 830 MPa at this time. Therefore, whenchemical strengthening is performed on both the top surface and bottomsurface of the glass plate under the same conditions, the depth of thecompressive stress in the top surface is deeper than that in the bottomsurface, and the surface compressive stress of the top surface isaccordingly smaller than that of the bottom surface. Therefore, whenimpact is applied to the glass plate, the top surface is more easilybroken than the bottom surface is.

4-2. Adhesive Layer

The adhesive layer 3 need only be capable of fixing the glass plate 10to the display panel 500 with sufficient strength. Specifically, it ispossible to use an adhesive layer constituted by a resin havingtackiness at an ordinary temperature such as an acrylic resin, arubber-based resin, or a resin having a desired glass transitiontemperature formed through copolymerization of a methacrylic monomer andan acrylic monomer. Examples of the acrylic monomer include methylacrylate, ethyl acrylate, butyl acrylate, stearyl acrylate, and2-ethylhexyl acrylate, and examples of the methacrylic monomer includeethyl methacrylate, butyl methacrylate, isobutyl methacrylate, andstearyl methacrylate. If the adhesive layer is applied through heatlamination or the like, an organic substance that softens at thelamination temperature may be used. When a resin formed throughcopolymerization of a methacrylic monomer and an acrylic monomer isused, the glass transition temperature thereof can be adjusted bychanging the blend ratio of the monomers. The adhesive layer 71 maycontain an ultraviolet absorber.

The thickness of the adhesive layer 3 can be set to, for example, 10 to500 μm, and is preferably 20 to 350 μm. In particular, when the adhesivelayer 3 has a small thickness, the distance from the display panel 500to the outermost surface of the cover member 100 is small, and thus animage displayed on the display panel 500 can be clearly seen. On theother hand, it is not preferable that the thickness of the adhesivelayer 3 is excessively small because the glass plate and the displaypanel 500 will be fixed to each other with reduced strength.

It is preferable that the refractive index of the adhesive layer 3 islarger than the refractive index of air and smaller than the refractiveindex of the glass plate 10. This makes it possible to suppressdistortion of an image displayed on the display panel.

4-3. Optical Layer

Next, the optical layer will be described. Hereinafter, three types ofanti-glare films will be described as examples of the optical layer. Inthe following description, the wording “substantially in parallel with”means that the angle formed between two planes of interest is 30° orless, 20° or less, or particularly 10° or less. The wording “maincomponent” means a component that is contained in an amount of 50% ormore or 80% or more in terms of mass. The wording “substantiallycomposed of” means that a component is contained in an amount of 80% ormore, 90% or more, or particularly 95% or more, in terms of mass. As isthe case with the above-described main surfaces of the glass plate, the“main surfaces” of a plate-shaped particle refer to a pair of surfaceson the front and back sides of the plate-shaped particle. The definitionof “plateau-shaped” will be described later with reference to FIG. 8 .

4-3-1. First Anti-Glare Film

First, a first anti-glare film 20 will be described with reference toFIG. 2 . FIG. 2 is a partial cross-sectional view of a glass plate onwhich an anti-glare film is layered. Although the anti-glare film 20 isformed directly on the second surface of the glass plate 10 in theexample shown in FIG. 2 , another film may be provided between the glassplate 10 and the anti-glare film 20. The anti-glare film 20 includesparticles 1 and a matrix 2. The anti-glare film 20 may contain voids.The voids may be contained inside the matrix 2, or may be in contactwith the particles 1 and matrix 2.

4-3-1-1. Particles

The particles 1 may be plate-shaped particles. The particles 1 may besubstantially composed of plate-shaped particles. Note that some of theparticles 1 may have a shape other than a plate shape such as aspherical shape, but the particles 1 may include no spherical particlesand the like and be composed of only plate-shaped particles. FIG. 3shows an example of the particle 1 having a plate shape. The particle 1has a pair of main surfaces is. The pair of main surfaces is aresubstantially in parallel with each other. The main surfaces is can besubstantially flat surfaces. However, steps or minute protrusions anddepressions may be present on the main surfaces is. Note that a particleconstituted by spherical silicon oxide particles that are linkedtogether does not have a plate-shaped external shape but has achain-shaped external shape, and thus is not considered as aplate-shaped particle.

The thickness 1 t of the particle 1 corresponds to the distance betweenthe pair of main surfaces is and is within a range of 0.3 nm to 3 nm.The thickness 1 t is preferably 0.5 nm or more and more preferably 0.7nm or more, and is also preferably 2 nm or less and more preferably 1.5nm or less. In a case where the thickness it varies depending onlocation, it is sufficient that the average of the maximum thickness andthe minimum thickness is taken as the thickness 1 t.

The average diameter d of the main surface 1 s of the particle 1 iswithin a range of 10 nm to 1,000 nm. The average diameter d of the mainsurface 1 s preferably 20 nm or more, and more preferably 30 nm or more.Also, the average diameter d is preferably 700 nm or less, and morepreferably 500 nm or less. The average of the minimum value and themaximum value of the values of diameters passing through the center ofgravity of the main surface is can be taken as the average diameter d ofthe main surface 1 s.

The average aspect ratio of the particle 1 can be calculated as d/t.Although the average aspect ratio is not particularly limited, it ispreferably 30 or more, and more preferably 50 or more. The averageaspect ratio may also be 1000 or less, or 700 or less.

The particle 1 may be a phyllosilicate mineral particle. Aphyllosilicate mineral contained in the phyllosilicate mineral particleis also called a layered silicate mineral. Examples of thephyllosilicate mineral include: kaolin minerals such as kaolinite,dickite, nacrite, and halloysite; serpentines such as chrysotile,lizardite, and amesite; dioctahedral smectites such as montmorilloniteand beidellite; trioctahedral smectites such as saponite, hectorite, andsauconite; dioctahedral micas such as white mica, palagonite, illite,and celadonite; trioctahedral micas such as phlogopite, annite, andlepidolite; dioctahedral brittle micas such as margarite; trioctahedralbrittle micas such as clintonite and anandite; dioctahedral chloritessuch as donbassite; di-tri-octahedral chlorites such as cookeite andsudoite; trioctahedral chlorites such as clinochlore and chamosite;pyrophyllite; talc; dioctahedral vermiculite; and trioctahedralvermiculite. It is preferable that the phyllosilicate mineral particlecontains a mineral belonging to smectites, kaolins, and talc. Amongminerals belonging to smectites, montmorillonite is favorable. Note thatmontmorillonite belongs to the monoclinic system, kaolins belong to thetriclinic system, and talc belongs to the monoclinic system or triclinicsystem.

In the anti-glare film 20, the main surfaces is of the particles 1 areoriented substantially in parallel with the second surface of the glassplate 10. The particles 1 are considered to be oriented substantially inparallel as a whole as long as 80% or more, 85% or more, or particularly90% or more, of the particles in terms of the number of particles areoriented substantially in parallel, even if the rest of particles arenot oriented substantially in parallel. When it is determined whether ornot the particles 1 are arranged substantially in parallel, it isdesirable to confirm the orientations of thirty, preferably fifty,plate-shaped particles.

In the case where the particle 1 is a phyllosilicate mineral particle,the (001) plane among the crystal planes of the phyllosilicate mineralmay be oriented along the second surface of the glass plate 10. Such aplane orientation can be confirmed through X-ray diffraction analysis.

4-3-1-2. Matrix

It is preferable that the matrix 2 contains silicon oxide, which is anoxide of Si, as the main component. The matrix 2 containing siliconoxide as the main component is suitable for reducing the refractiveindex of the film and reducing the reflectivity of the film. The matrix2 may also contain other components in addition to silicon oxide, andmay also contain a component that contains silicon oxide as a portionthereof.

The component that contains silicon oxide as a portion thereof is, forexample, a component that includes a portion constituted by siliconatoms and oxygen atoms and in which an atom other than a silicon atomand an oxygen atom, a functional group, or the like is linked to asilicon atom or oxygen atom in this portion. Examples of the atom otherthan a silicon atom and an oxygen atom include a nitrogen atom, a carbonatom, a hydrogen atom, and metallic elements listed in the nextparagraph. Examples of the functional group include organic groups thatare listed as R in a paragraph below. Strictly speaking, such acomponent is not silicon oxide because it is not composed only of asilicon atom and an oxygen atom. However, in describing thecharacteristics of the matrix 2, treating a silicon oxide portion thatis composed of a silicon atom and an oxygen atom as a “silicon oxide” isappropriate and is also consistent with usage in the field. In thisspecification, the silicon oxide portion is also treated as a siliconoxide. As is clear from the above description, the atomic ratio betweensilicon atoms and oxygen atoms in a silicon oxide need not bestoichiometric (1:2).

The matrix 2 can contain a metal oxide other than silicon oxide, orspecifically, a metal oxide component or a metal oxide portion thatcontains an element other than silicon. Although metal oxides that canbe contained in the matrix 2 are not particularly limited, examplesthereof include oxides of at least one metallic element selected fromthe group consisting of Ti, Zr, Ta, Nb, Nd, La, Ce, and Sn. The matrix 2may contain an inorganic compound component other than an oxide,examples of which include a nitride, a carbide, and a halide, or maycontain an organic compound component.

A metal oxide such as silicon oxide can be formed from a hydrolyzableorganic metal compound. An example of a hydrolyzable silicon compound isa compound represented by Formula (1).

R_(n)SiY_(4-n)  (1)

R is an organic group including at least one selected from an alkylgroup, a vinyl group, an epoxy group, a styryl group, a methacryloylgroup, and an acryloyl group. Y is a hydrolyzable organic group that isat least one selected from an alkoxy group, an acetoxy group, analkenyloxy group, and an amino group, or a halogen atom. The halogenatom is preferably Cl. n is an integer from 0 to 3 and is preferably 0or 1.

R is preferably an alkyl group. For example, an alkyl group having 1 to3 carbon atoms is preferable, and a methyl group is particularlypreferable. Y is preferably an alkoxy group. For example, an alkoxygroup having 1 to 4 carbon atoms is preferable, and a methoxy group andan ethoxy group are particularly preferable. Two or more compoundsrepresented by the formula above may also be used in combination. As anexample of this combination, a tetraalkoxysilane, where n is 0, and amonoalkyltrialkoxysilane, where n is 1, may be used together.

After hydrolysis and polycondensation, the compound represented byFormula (1) forms a network structure in which silicon atoms are linkedto one another via oxygen atoms. In this structure, the organic groupsrepresented by R are contained in a state of being directly linked tosilicon atoms.

4-3-1-3. Physical Properties of First Anti-Glare Film

The ratio of the particles 1 to the matrix 2 in the anti-glare film 20in terms of mass is, for example, 0.05 to 10, 0.05 to 7, or preferably0.05 to 5. Although the volume ratio of the voids in the anti-glare film20 is not particularly limited, it may be 10% or more, or 10 to 20%.However, the voids need not necessarily be present.

Although the thickness of the anti-glare film 20 is not particularlylimited, it is suitable that the anti-glare film 20 has a thickness of,for example, 50 nm to 1,000 nm, 100 nm to 700 nm, or particularly 100 nmto 500 nm, from the viewpoint that the anti-glare properties are likelyto be appropriately obtained, for example. It is preferable that theanti-glare film 20 has a thickness that is smaller than or equal to theabove-described upper limit in order to orient the main surfaces of theplate-shaped particles substantially in parallel with a substrate. Inthe case of a thick film, there is a strong tendency for plate-shapedparticles to be oriented in a random manner.

It is preferable that minute protrusions and depressions are present ona surface 20 s of the anti-glare film 20. The anti-glare properties canbe expected to be increased due to the minute protrusions anddepressions. However, the development of the protrusions and depressionson the surface 20 s is suppressed due to the particles 1 being orientedalong the second surface of the glass plate 10. The surface roughness ofthe surface 20 s of the anti-glare film 20, which is determined as Ra,is 20 nm to 120 nm, 30 nm to 110 nm, or preferably 40 nm to 100 nm. Rais the arithmetic average roughness of a roughness curve determined inaccordance with JIS B0601: 2001. For example, if particles are orientedin a random manner, the surface roughness Ra will be larger than theabove-described range.

The surface 20 s has an Rsm of more than 0 μm and 35 μm or less, 1 μm to30 μm, or preferably 2 μm to 20 μm. Rsm is the average length ofroughness curve elements determined in accordance with JIS B0601: 2001.If Rsm is not excessively large, the appearance of what is known assparkles can be favorably suppressed.

Sparkles are bright spots that appear depending on the relationshipbetween the minute protrusions and depressions for imparting theanti-glare properties and the pixel size of the display panel. Thesparkles are observed as light that irregularly flickers with a changein the relative positions between a display device and the user's eyes.The sparkles have become apparent with an increase in resolution ofdisplay devices. The anti-glare film 20 having an Ra and an Rsm that arewithin the above-described ranges is particularly suitable for reducinggloss and haze with good balance while suppressing the appearance ofsparkles.

4-3-1-4. Optical Properties of Cover Member

The gloss can be evaluated based on the specular gloss. The 60° speculargloss of the glass plate 10 is, for example, 60 to 130%, 70 to 120%, orparticularly 80 to 110% or 85 to 100%. These specular gloss values aremeasured on the surface 10 s on which the anti-glare film 20 is formed.The haze ratio of the glass plate 10 is, for example, 20% or less, 15%or less, or particularly 10% or less, or may be 1 to 8%, 1 to 6%, orparticularly 1 to 5%, in certain cases.

The 60° specular gloss G and the haze ratio H (%) preferably satisfyRelational Expression (a), more preferably Relational Expression (b),and even more preferably Relational Expression (c). G and H may satisfyRelational Expression (d).

H≤−0.2G+25  (a)

H≤−0.2G+24.5  (b)

H≤−0.2G+24  (c)

H≤−0.2G+18  (d)

Note that the gloss can be measured in conformity with “Method 3(Specular gloss at 60 degrees)” of “Specular glossiness—Methods ofmeasurement” in JIS Z8741-1997, and the haze can be measured inconformity with JIS K7136: 2000.

4-3-2. Second Anti-Glare Film

Next, a second anti-glare film will be described with reference to FIGS.4 and 5 . FIGS. 4 and 5 are partial cross-sectional views of a glassplate on which a second anti-glare film is layered. Although anti-glarefilms 30 and 40 are each formed directly on the second surface of theglass plate 10 in FIGS. 4 and 5 , other films may be provided betweenthe glass plate 10 and the anti-glare film and the glass plate 10 andthe anti-glare film 40. The anti-glare films 30 and 40 include particles5 and the matrix 2. The anti-glare films 30 and 40 may contain voids.The voids may be contained inside the matrix 2, or may be in contactwith the particles 5 and matrix 2.

In the anti-glare film 30, the particles 5 are piled up in the thicknessdirection of the film in all the regions, whereas the anti-glare film 40includes a region 40 a in which the particles 5 are piled up in thethickness direction of the film and a region 40 b in which the particles5 are not piled up in that direction or the particles 5 are not present.The region 40 b may be a region having a surface 40 s that issubstantially in parallel with the second surface of the glass plate 10and from which the particles 5 are not exposed, instead of a region inwhich the particles 5 are not piled up in that direction or theparticles 5 are not present. The region 40 b may spread over, forexample, 0.25 μm² or more, 0.5 μm² or more, or particularly 1 μm² ormore. Note that, in at least some of the regions 40 a of the anti-glarefilms 30 and 40, the particles 5 are piled up to a height that is 5times or more, or 7 times or more, as high as the average particlediameter of the particles 5.

4-3-2-1. Particles

Although the shape of the particle 5 is not particularly limited, aspherical shape is preferable. The particles 5 may be substantiallycomposed of spherical particles. However, some of the particles 5 mayhave a shape other than a spherical shape such as a plate shape. Theparticles 5 may be composed of only spherical particles. Here, thespherical particles are particles in which a ratio of the longestdiameter passing through the center of gravity to the shortest diameterpassing through the center of gravity is 1 or more and 1.8 or less, orparticularly 1 or more and 1.5 or less, and its surface 1 s constitutedby a curved surface. The average particle diameter of the sphericalparticles may be 5 nm to 200 nm, nm to 100 nm, or particularly 20 nm to60 nm. The average particle diameter of the spherical particles isdetermined as an average of the diameters of the particles(specifically, the diameter of the particle is an average value of theabove-described shortest diameter and longest diameter), and it isdesirable that the average particle diameter is determined using thirty,preferably fifty, particles based on an SEM image.

Preferable ranges of the thickness t, main surface average diameter d,and aspect ratio d/t of a plate-shaped particle that may be included asa portion of the particles are the same as those in the case of thefirst anti-glare film.

Although a material for forming the particles 5 is not particularlylimited, it is preferable that the material contains a metal oxide,particularly silicon oxide. However, the metal oxide may include anoxide of at least one metallic element selected from the groupconsisting of Ti, Zr, Ta, Nb, Nd, La, Ce, and Sn, for example.

The particles 5 can be supplied to the anti-glare films 30 and 40 from adispersion liquid of particles 5. In this case, it is preferable to usea dispersion liquid in which the particles 5 are dispersed in a state ofbeing separate from one another. Use of a dispersion liquid in which theparticles do not aggregate rather than a dispersion liquid in which theparticles are linked together in a chain shape is suitable for achievingdesirable aggregation of the particles in the anti-glare films 30 and40. The reason for this is that the particles that are separate from oneanother are likely to move along with volatilization of a liquid such asa dispersion medium and are likely to form, in the film, an aggregatethat is suitable for achieving favorable properties.

4-3-2-2. Matrix

The matrix 2 is the same as that of the above-described first anti-glarefilm 20. However, it is preferable that the matrix 2 of the secondanti-glare films 30 and 40 contains a nitrogen atom. It is preferablethat a nitrogen atom is contained as a portion of an organic compoundcomponent or a functional group, particularly a nitrogen-atom-containingfunctional group. The nitrogen-atom-containing functional group ispreferably an amino group. A nitrogen atom can make up a portion of ahighly reactive functional group particularly in a raw material forforming a matrix that contains a metal oxide such as silicon oxide as amain component. Such a functional group can promote aggregation of theparticles 5 during film formation and play a role in achieving adesirable form of the aggregate of the particles 5.

A metal oxide such as silicon oxide can be formed from a hydrolyzableorganic metal compound. An example of a hydrolyzable silicon compound isa compound represented by Formula (1).

A nitrogen atom can also be supplied to the anti-glare films 30 and 40from a silicon-atom-containing compound, specifically anamino-group-containing silane coupling agent. This compound can berepresented by, for example, Formula (2).

A_(k)B_(m)SiY_(4-k-m)  (2)

A is an organic group containing an amino group. The amino group may bea primary, secondary, or tertiary amino group. A is anamino-group-containing hydrocarbon, for example, preferably an alkylgroup or alkenyl group in which some atoms are substituted with an aminogroup, more preferably an alkyl group or alkenyl group in which ahydrogen atom is substituted with an amino group, and particularlypreferably an alkyl group or alkenyl group having an amino group at itsterminus. The alkyl group and the alkenyl group may be linear orbranched. Preferable specific examples of A include co-aminoalkyl groupshaving an amino group at the terminus of an alkyl group, andN-ω′-(aminoalkyl)-ω-aminoalkyl groups obtained by substituting ahydrogen atom of the amino group of the co-aminoalkyl group with anotheraminoalkyl group. It is preferable that A contains a carbon atom as anatom to be linked to the silicon atom. In this case, a hydrocarbon grouptypified by alkyl groups and alkenyl groups can be provided between thenitrogen atom and the silicon atom. In other words, the nitrogen atommay be linked to the silicon atom contained in silicon oxide via ahydrocarbon group. A is particularly preferably a γ-aminopropyl group oran N-(2-aminoethyl)-3-aminopropyl group.

B may be one of the organic groups listed above as R, or an alkyl groupor alkenyl group. The alkyl group or alkenyl group may be branched, andsome of hydrogen atoms thereof may be substituted. B is preferably anon-substituted alkyl group, more preferably a linear alkyl group whosecarbon chain has 1 to 3 carbon atoms, and even more preferably a methylgroup. Y is as described above. k is an integer from 1 to 3, m is aninteger from 0 to 2, and k+m is an integer from 1 to 3. k is 1, and m is0 or 1. Note that, when A is a γ-aminopropyl group, it is preferablethat k is 1 and m is 0, and when A is N-(2-aminoethyl)-3-aminopropylgroup, it is preferable that k is 1 and m is 0 or 1.

After hydrolysis and polycondensation, the compound represented byFormula (2) forms a network structure in which silicon atoms are linkedto one another via oxygen atoms. When used together with the compoundrepresented by Formula (1), the compound represented by Formula (2)makes up a portion of the network structure. In this structure, theorganic groups represented by A are contained in a state of beingdirectly linked to silicon atoms.

It is considered that the organic group represented by A attractsparticles and promotes aggregation of the particles duringvolatilization of a solvent of a coating solution.

The first and second anti-glare films 20, 30, and 40 having theabove-described compositions can be said to be organic-inorganiccomposite films.

4-3-2-3. Physical Properties of Second Anti-Glare Film

Although the ratios of the particles 5 to the matrix 2 in the anti-glarefilms 30 and 40, the film thicknesses of the anti-glare films 30 and 40,the Ra of the surfaces 30 s and 40 s, and the Rsm of the surfaces 30 sand 40 s are not particularly limited, the ranges therefor may be thesame as those in the case of the above-described first anti-glare film20.

In the anti-glare films 30 and 40, the particles 5 locally aggregate andlie on top of one another, and thus this portion of the film has anincreased thickness, whereas the particles 5 do not lie on top of oneanother in another portion, and thus the thickness of the film islocally reduced. In the anti-glare films 30 and 40, a difference inheight measured from the second surface of the glass plate 10 betweenthe highest portion and the lowest portion may be three times or more,or four times or more, as large as the average particle diameter of theparticles 5.

In the region 40 b of the anti-glare film 40, the particles are notpiled up in the thickness direction of the film, or the particles arenot present. In the latter case, the region 40 b of the film 40 may becomposed of only the matrix 2. The area ratio of the region 40 b to theregion on which the anti-glare film 40 is formed may be, for example, 5to 90%, 10 to 70%, or particularly 20 to 50%.

4-3-2-4. Optical Properties of Cover Member

The gloss can be evaluated based on the specular gloss. The 60° speculargloss of the glass plate 10 is, for example, 60 to 130%, 70 to 120%, orparticularly 80 to 110% or 85 to 100%. These specular gloss values aremeasured on the second surfaces of the glass plates on which theanti-glare films 30 and 40 are formed. The haze ratio of the glass plate10 is, for example, 20% or less, 15% or less, or particularly 10% orless, or may be 1 to 8%, 1 to 6%, or particularly 1 to 5%, in certaincases.

The 60° specular gloss G and the haze ratio H (%) preferably satisfyRelational Expression (a), and more preferably Relational Expression(b).

H≤−0.2G+25  (a)

H≤−0.2G+24.5  (b)

The numbers of Japanese Industrial Standards that are referred to formeasurement of the gloss and haze are as described above.

4-3-2-5. Load Curve Parameters

Cover glass 200 and 300 in which the second anti-glare film is layeredcan have the following characteristics regarding load curve parametersin conformity with ISO25178. Note that, as specified in ISO25178, in aload curve, the frequencies at certain heights are accumulated from ahigher side and are expressed in percentage with the total number ofpieces of data at all the heights being taken as 100. Based on the loadcurve, a load area ratio at a certain height C is given as Smr(C). Aline having the smallest slope among lines on which a difference betweenthe Smr values at any two heights is 40% is defined as an equivalentline. At this time, a difference in height between a point on theequivalent line at a load area ratio of 0% and a point on the equivalentline at a load area ratio of 100% is defined as a level difference Sk ina core portion. A load area ratio at which a peak above the core portionis divided from the core portion is defined as Smr1, and a load arearatio at which a valley below the core portion is conversely dividedfrom the core portion is defined as Smr2. Surface heights at load arearatios of 20, 40, 60, and 80% are respectively defined as BH20, BH40,BH60, and BH80.

Smr1 may be 1 to 40% or 3 to 35%, or 10 to 30% in certain cases. BH20is, for example, 0.04 μm to 0.5 μm, 0.06 μm to 0.5 μm, or preferably0.12 μm to 0.3 μm. BH80 is, for example, −0.3 μm to 0 μm, −0.3 μm to−0.05 μm, or preferably −0.25 μm to −0.12 μm.

4-3-3. Third Anti-Glare Film

Next, a third anti-glare film will be described with reference to FIGS.6 and 7 . FIG. 6 is a partial cross-sectional view of a glass plate onwhich a third anti-glare film is layered, and FIG. 7 is a partialcross-sectional view showing another example of a glass plate on which athird anti-glare film is layered. As shown in FIGS. 6 and 7 , covermembers 400 and 500 each include a glass plate 10.

The cover members 400 and 500 also include anti-glare films 50 and 60provided on the glass plate 10, respectively. Although the anti-glarefilms 50 and 60 are each formed directly on the main surface 10 s of theglass plate 10 in FIGS. 6 and 7 , other films may be provided betweenthe glass plate 10 and the anti-glare film 50 and the glass plate 10 andthe anti-glare film 60. The anti-glare films 50 and 60 include theparticles 5 and the matrix 2. The anti-glare films 50 and 60 may containvoids. The voids may be contained inside the matrix 2, or may be incontact with the particles 5 and matrix 2.

The anti-glare films 50 and 60 include first regions 50 p and 60 p,respectively, and also include second regions 50 v and 60 v,respectively. In the first regions 50 p and 60 p, the particles 5 arepiled up in the thickness direction of the anti-glare films 50 and 60.When the anti-glare films 50 and 60 are observed from the front sidethereof in the thickness direction, the second regions 50 v and 60 vrespectively surround the first regions 50 p and 60 p. However, thesecond regions 50 v and 60 v may be respectively surrounded by the firstregions 50 p and 60 p. The first regions 50 p and 60 p and the secondregions 50 v and 60 v are arranged such that, for example, one of thefirst region and the second region is provided between a plurality ofthe other regions that are separated from each other. This structure mayalso be referred to as a sea-island structure. The second regions 50 vand 60 v are valley-shaped regions whose surfaces are recessed relativeto the surrounding first regions. Accordingly, the island portions inthe sea-island structure protrude from the sea portions when the firstregions 50 p and 60 p correspond to the island portions, whereas theisland portions are recessed from the sea portions when the secondregions 50 v and 60 v correspond to the island portions. Fewer particlesare piled up in the second regions 50 v and 60 v compared with the firstregions 50 p and 60 p. The second regions 50 v and 60 v may include aportion 50 t in which the particles 5 are piled up (see FIG. 6 ). Thesecond regions 50 v and 60 v may include a portion in which theparticles 5 are not piled up or the particles 5 are not present (seeFIGS. 6 and 7 ). At least some of the second regions 50 v and 60 v maybe composed of a portion in which the particles 5 are not piled up orthe particles 5 are not present. In the case of the first regions 50 pand 60 p, at least some of them or 50% or more thereof in terms of thenumber of regions, or all of them may be composed of a plateau-shapedregion.

The term “plateau-shaped” means that, when the film is observed under anSEM, the upper portion of a protrusion on the anti-glare films 50 and 60seems to have a plateau shape. Strictly speaking, this term means that arelationship L2/L1≥0.75, particularly L2/L1≥0.8, is satisfied in thecross section of the film. Here, as shown in FIG. 8 , L1 is a length ofa portion located at a height corresponding to 50% of the height H of aprotrusion, and L2 is a length of a portion located at a heightcorresponding to 70%, preferably 75%, of the height H of the protrusion.As shown in FIG. 8 , L2 may be divided into two or more portions withrespect to one L1. In this case, the total length of the two or moreportions is taken as L2.

Boundaries 50 b and 60 b between the first regions 50 p and 60 p and thesecond regions 50 v and 60 v can be determined based on averagethicknesses T of the anti-glare films 50 and 60 (see FIG. 7 ). Theaverage thickness T can be measured using a laser microscope asdescribed later. Based on the intervals between the boundaries 50 b andthe intervals between the boundaries 60 b, widths Wp of the firstregions 50 p and 60 p and widths Wv of the second regions 50 v and 60 vare determined.

The width Wp may be 5 μm or more, 7.7 μm or more, or preferably 10 μm ormore. The width Wv may be 3.5 μm or more, 7 μm or more, or preferably 10μm or more. When the width Wp is large, the haze ratio tends to decreasebecause the anti-glare film is likely to directly transmit visible lightincident thereon. When the width Wv is large, gloss tends to decreasebecause the anti-glare film moderately scatters visible light incidentthereon. A film having a width Wp of 10 μm or more and a width Wv of 10μm or more is particularly suitable for achieving both low haze ratioand low gloss.

The first regions 50 p and 60 p and the second regions 50 v and 60 veach may spread over an area of, for example, 0.25 μm² or more, 0.5 μm²or more, or particularly 1 μm² or more, or 5 μm² or more or 10 μm² ormore in certain cases.

The anti-glare films 50 and 60 include first regions 50 p and 60 p,respectively, and also include second regions 50 v and 60 v,respectively. The area ratio of the second regions 50 v and 60 v to theregion on which the anti-glare film 40 is formed may be, for example, 5to 90%, 10 to 70%, or particularly 20 to 50%. The anti-glare films 50and 60 may be composed of only the first regions 50 p and 60 p and thesecond regions 50 v and 60 v.

4-3-3-1. Particles

The particles 5 are the same as those in the description of the secondanti-glare film.

4-3-3-2. Matrix

The matrix 2 is the same as those in the descriptions of the first andsecond anti-glare films. However, unlike the second anti-glare film, itis less necessary to add a nitrogen atom to promote aggregation of theparticles 5 in the third anti-glare film. Accordingly, it is preferableto form a metal oxide such as silicon oxide used to form the matrix 2from a hydrolyzable organic metal compound, particularly a compoundrepresented by Formula (1). The matrix 2 may be substantially composedof silicon oxide.

4-3-3-3. Physical Properties of Third Anti-Glare Film

Although, in the anti-glare films 50 and 60, the ratios of the particles5 to the matrix 2, the film thicknesses, the Ra of the surfaces 50 s and60 s, and the Rsm of the surfaces 50 s and 60 s are not particularlylimited, the ranges therefor may be the same as those in thedescriptions of the first and second anti-glare films. In the anti-glarefilms 50 and 60, a difference in height measured from the main surface10 s of the glass plate 10 between the highest portion and the lowestportion may be three times or more, or four times or more, as large asthe average particle diameter of the particles 5.

4-3-3-4. Optical Properties of Cover Member

The gloss can be evaluated based on the specular gloss. The 60° speculargloss of the glass plate 10 is, for example, 60 to 130%, 70 to 120%, orparticularly 80 to 110% or 85 to 100%. These specular gloss values aremeasured on the surfaces 10 s on which the anti-glare films 50 and 60are formed. The haze ratio of the glass plate 10 is, for example, 20% orless, 15% or less, or particularly 10% or less, or may be 1 to 8%, 1 to6%, or particularly 1 to 5%, in certain cases.

The 60° specular gloss G and the haze ratio H (%) preferably satisfyRelational Expression (a), more preferably Relational Expression (b),and even more preferably Relational Expression (c). G and H may satisfyRelational Expression (d).

H≤−0.2G+25  (a)

H≤−0.2G+24.5  (b)

H≤−0.2G+24  (c)

H≤−0.2G+18  (d)

The numbers of Japanese Industrial Standards that are referred to formeasurement of the gloss and haze are as described above.

4-4. Method for Forming Optical Layer

Although a method for forming an optical layer is not particularlylimited, the optical layer can be formed as follows, for example. First,a material (e.g., tetraethoxysilane) for forming the above-describedmatrix is dissolved under an acidic condition to form a solution, andthus a matrix precursor solution is produced. Also, a dispersion liquidcontaining the above-described particles (e.g., smectite dispersionliquid) is diluted with ethanol or the like to produce a fine-particledispersion liquid. Then, the matrix precursor solution and thefine-particle dispersion liquid are mixed to produce a coating solutionfor an optical layer.

Next, the coating solution is applied to the second surface of the glassplate 10 that has been washed. Although the application method is notparticularly limited, flow coating, spray coating, spin coating, or thelike can be used, for example. After that, the glass plate to which thecoating solution has been applied is dried at a predeterminedtemperature (e.g., 80 to 120° C.) in an oven or the like in order to,for example, volatilize the alcohol from the solution, and then sinteredat a predetermined temperature (e.g., 400 to 650° C.) for the purpose ofhydrolysis and organic chain decomposition, for example. Thus, anoptical layer can be obtained.

5. Features

The display device according to this embodiment can exhibit thefollowing effects. That is, the anti-glare films 20, 30, 40, 50, and 60are layered as an optical layer in the cover members 100, 200, 300, 400,and 500, and this enables an image displayed on the display panel 500 tobe clearly seen. The glass plate 10 and the display panel 500 aredirectly fixed to each other using the adhesive layer 3 with no airlayer being located therebetween, and this also enables an imagedisplayed on the display panel 500 to be clearly seen.

Furthermore, in this display device, the glass plate is chemicallystrengthened, and the depth of the compressive stress in the secondsurface, which faces the outside (a driver side), is larger than that inthe first surface. In particular, the glass plate 10 is manufacturedusing a float process, and the top surface in which the concentration oftin oxide is larger corresponds to the second surface and faces theoutside. Therefore, when chemical strengthening is performed, the depthof the compressive stress layer in the second surface can be made largerthan that in the first surface. Therefore, the surface of the covermember that faces the vehicle interior side decreases in strength, andis easily broken when impact is applied thereto. Accordingly, when thehead of a driver or a passenger sitting on the passenger seat collidesagainst the display device due to, for example, an accident, the glassplate 10 is easily broken due to impact with the head, thus making itpossible to reduce impact on the head.

Since the anti-glare films 20, 30, 40, 50, and 60 are organic-inorganiccomposite films, deterioration of the anti-glare films 20, 30, 40, 50,and 60 can be suppressed due to reaction between the organic componentscontained in the films and tin oxide contained in the surface of theglass plate 10.

6. Modified Examples

Although an embodiment of the present invention has been describedabove, the present invention is not limited to the embodiment above, andvarious modifications can be carried out without departing from the gistof the invention. Note that the following modified examples can becombined as appropriate.

6-1

The configuration of the housing 4 is not particularly limited, and itis sufficient that the display panel 500 and the backlight unit 6 can behoused therein. An organic EL panel, a plasma display panel, anelectronic ink-type panel, and the like, for example, can also be usedas the display panel 500 instead of employing the above-described liquidcrystal panel. If the display panel 500 is constituted by a displaypanel other than a liquid crystal panel, there is no need to use thebacklight unit 6. Instead of the adhesive layer 3, air may be providedbetween the display panel 500 and the cover member 100.

6-2

Although the cover member is configured to come into contact with thehousing 4 in the embodiment above, the cover member may also beconfigured to come into contact with only the display panel.

6-3

The glass plate 10 can also be provided with, for example, a shieldlayer 9 as shown in FIG. 9 such that a portion of the display area ofthe display panel 500 can be seen. This shield layer 9 is provided withat least one opening 91 or cutout 92, and an image displayed on thedisplay panel 500 can be seen through this opening 91 or cutout 92. Itis sufficient that this shield layer 9 is formed on at least one of thefirst surface and the second surface of the glass plate 10. The opticallayer can be layered so as to cover the opening 91 and cutout 92. Also,the optical layer can be formed on the shield layer 9. Although there isno particular limitation on the material for forming the shield layer 9,the shield layer 9 can be formed using, for example, a ceramic sheetmaterial with a dark color such as black, brown, gray, or dark blue.

6-4

Although the organic-inorganic composite film 20, 30, 40, 50, or 60having anti-glare properties is layered, as an optical layer, on thesecond surface of the glass plate in the embodiment above, theanti-glare properties or anti-reflection properties can also be impartedby, for example, forming minute protrusions and depressions on thesecond surface of the glass plate 10 through etching or the like. Thelayer with such protrusions and depressions also corresponds to theoptical layer of the present invention. Although the anti-glare filmshave been described as an example of the optical layer in the embodimentabove, another functional film may also be used as the optical layer.Examples thereof include known anti-reflection films, anti-foggingfilms, and heat reflection films.

6-5

Although a glass plate manufactured using a float process is used in theembodiment above, there is no particular limitation on a method formanufacturing a glass plate. It is sufficient that at least chemicalstrengthening is performed, and the depth of the compressive stresslayer in the second surface, which faces the outside, is larger thanthat in the first surface.

6-6

Although the display device of the present invention is applied to avehicle-mounted display device in the description of the embodimentabove, there is no limitation thereto. The display device of the presentinvention can be applied to display devices in general that are usedtogether with the above-described display panel. The display device canalso be used as a touch panel display by providing a touch panelthereon. Accordingly, the above-described cover member can also beapplied to various display devices.

LIST OF REFERENCE NUMERALS

-   -   10 Glass plate    -   20, 30, 40, 50, 60 Anti-glare film (optical layer)    -   500 Display panel

1. A display device, comprising: a display panel; and a cover memberdisposed on the display panel, wherein the cover member includes: aglass plate that is chemically strengthened and has a first surface anda second surface in which a depth of a compressive stress layer (dol) islarger than that in the first surface; and an optical layer that islayered on the second surface of the glass plate and faces the outside.2. The display device according to claim 1, wherein the glass plate ismanufactured using a float process, and a concentration of tin oxide inthe first surface 1 s larger than that in the second surface.
 3. Thedisplay device according to claim 1, wherein the optical layer is anorganic-inorganic composite film.
 4. The display device according toclaim 1, wherein the optical layer contains at least a matrix andparticles, and the particles form protrusions and depressions on asurface of the optical layer on a side opposite to the second surface.5. The display device according to claim 4, wherein the optical layerincludes a first region in which the particles are piled up in athickness direction of the layer, and a valley-shaped second region thatsurrounds the first region or is surrounded by the first region.
 6. Thedisplay device according to claim 5, wherein the first region is aplateau-shaped region.
 7. The display device according to claim 5,wherein the second region includes a portion in which the particles arenot piled up or the particles are not present.
 8. The display deviceaccording to claim 5, wherein the first region has a width of 7.7 μm ormore, and the second region has a width of 7 μm or more.
 9. (canceled)10. The display device according to claim 4, wherein the particles aresubstantially composed of plate-shaped particles, each of theplate-shaped particles has a thickness within a range of 0.3 nm to 3 nmand a main surface average diameter within a range of 10 nm to 1,000 nm,and the main surfaces of the plate-shaped particles are orientedsubstantially in parallel with the second surface of the glass plate.11. The display device according to claim 4, wherein the optical layerincludes a region in which the particles are piled up in a thicknessdirection of the optical layer, and a region in which the particles arenot piled up or the particles are not present.
 12. The display deviceaccording to claim 11, wherein a difference in height measured from thesecond surface of the glass plate between the highest portion and thelowest portion of the optical layer is three times or more as large asthe average particle diameter of the particles.
 13. The display deviceaccording to claim 11, wherein Smr1 defined in ISO25178 is 10 to 30%.14. The display device according to claim 11, wherein a surface heightBH20 at a load area ratio of 20% defined in ISO25178 is within a rangeof 0.04 μm to 0.5 μm.
 15. The display device according to claim 11,wherein a surface height BH80 at a load area ratio of 80% defined inISO25178 is within a range of ˜0.3 μm to 0 μm.
 16. The display deviceaccording to claim 1, wherein the surface of the optical layer has anRsm of more than 0 μm and 35 μm or less, the Rsm being an average lengthof roughness curve elements determined in accordance with JIS B0601:2001.
 17. The display device according to claim 1, wherein the surfaceof the optical layer has an Ra within a range of 20 nm to 120 nm, the Rabeing an arithmetic average roughness of a roughness curve determined inaccordance with JIS B0601:
 2001. 18. The display device according toclaim 1, wherein the second surface of the glass plate has an Ra of 10nm or less, the Ra being an arithmetic average roughness of a roughnesscurve determined in accordance with JIS B0601:
 2001. 19. The displaydevice according to claim 1, wherein the matrix contains silicon oxideas a main component.
 20. The display device according to claim 1,wherein the glass plate has a thickness of 0.5 to 3 mm.
 21. A covermember to be included in a display device having a display panel,comprising: a glass plate that is manufactured using a float process,and has a first surface and a second surface in which a concentration oftin oxide is larger than that in the first surface; and an optical layerthat is layered on the second surface of the glass plate and faces theoutside.